The present invention relates to an air flow sensor, and particularly to an electronically controlled throttle body integrated air flow sensor which controls the amount of intake air in an internal combustion engine.
The prior art concerning the integration of the electronically controlled throttle body and the air flow sensor is disclosed in the Japanese Patent Application Laid-Open No. 4-350338.
Although the throttle valve opening controller of the electronically controlled throttle body and the air flow sensor are installed in the same body respectively in this prior art, they are functionally independent of each. Although a lot of errors are included in the air flow rate output signal of this air flow sensor usually, this output signal is supplied to the engine control unit as it is. Further, because the information interchange is not mutually done between the throttle valve opening information and the air flow rate signal, it is impossible to perform the self-fault diagnosis. In addition, it is not possible to perform the feedback-control of the throttle valve to become the best intake air flow, because the intake air flow signal is not input to the throttle valve controller in the conventional configuration.
In the air flow sensor, the amount of the intake air to the internal combustion engine is detected by a small detector compared with the air passage. Therefore, the error occurs in the air flow rate output signal of the air flow sensor when the turbulence or the drift or the backflow is caused even if the mass of air which flows in the air passage is the same. Because the output signal with this error is sent to the engine control unit, combustion cannot be controlled best. Therefore, the harmful exhaust gas is discharged.
A serious problem is caused due to the breakdown of the electronically controlled throttle body, so that the engine goes out of control. Therefore, the double or triple safety system and the fault diagnosis system are demanded. Further, the breakdown of the air flow sensor causes the internal combustion engine for the harmful exhaust gas to be discharged as mentioned above. In addition, it is required to control so as to obtain the best intake air flow, not to control according to the amount of the accelerator stepping, in order to suppress the discharge of such harmful exhaust gas
An object of the present invention is to provide an electronically controlled throttle body integrated air flow sensor, in which the air flow rate signal with extremely few errors is output to suppress the discharge of the harmful exhaust gas from the internal combustion engine, and the best amount of intake air is supplied to the internal combustion engine.
Another object of the present invention is to provide an electronically controlled throttle body integrated air flow sensor, in which it is possible to perform the self-diagnosis of the breakdown of the air flow sensor or the electronically controlled throttle so that the accident can be prevented beforehand.
In the device according to one aspect of the present invention, the air flow meter, the pressure gauge, the electronically controlled throttle body, and the microcomputer, etc. are integrated as one. The correction, the control, and the fault diagnosis of each measurement of the air flow rate etc. are done by the integrated microcomputer. It, therefore, becomes possible to produce the air flow sensor which can measure an accurate air flow rate at low man-hour and low-cost. The correction of the measurement to control the entire internal combustion engine or the entire car and the self-diagnosis done by the control unit so far is carried out by the air flow sensor itself. Therefore, the load of control unit is decreased. Further, wiring and a lot of power supplies become unnecessary because the information on throttle valve opening necessary for the correction can be obtained internally. Therefore, making to low-cost and the miniaturization become possible. Further, the matching man-hour can be decreased by setting the correction factor beforehand before building in the system.